Method for testing and producing the fluids of the earth formations encountered in wells



L ETAL AND PRODUCI IoNs- Filed Ma Patented Aug. 19,- 1941 METHOD FR TESTING AND PRODUCENG THE FLUIDS F THE EARTH FORMATIONS ENCOUNTERED IN WELLS -Elwin B.l Hall and Arthur L. Armentrout, Los Angeles, Calif., assignors, by direct and mesne assignments, to Security Engineering Co. Inc.,

a corporation of California Application March 10, 1939, Serial No. 260,952

Claims.

This invention has to do with the testing and producing of wells and has particular reference to a method for testing and producing the fluids of the earth formations encountered in wells. A general object of this invention is to provide a rapid, efficient and practical method for. determining the productivity of the earth formations encountered in Wells and for recovering or producing such fluids.

This application is a continuation in part of' our co-pending application Serial No. 80,696, led May 20, 1936.

Another object of this invention is to provide a simple, safe and commercially practical method for determining the productivity of the earth formations in a well and for producing or recovering the fluids from such formations, which method does not endanger the well and cannot necessitate expensive time consuming fishing operations. In the producing and testing of wells such as oil wells and gas wells it has been the common practice to install steel liners and casings and to utilize steel testing equipment. The steel liners andcasings are usually run into the well to extend into or through the producing strata and the testing equipment is usually arranged to extend into the open portion of the well bore. In many instances the steel liners,- casings and/or testing equipment become lodged, caughtor immovably fixed in the well. The steel equipment'thus caught in the well cannot be drilled up by. the well drilling equipment Yand attempts must .be made to'withdraw it or fish it from the well with fishing tools. Theseiishing operations are very expensive and-time consuming and in many cases fail or resultin the recovery of even a portion of the lost equipment.

Wherethe lost on caught equipment cannot he recovered by Afishing operations it is necessary to attempt to-.sidetrack the well past the caught `equipment and if this lfails the well must be Another 'object of this invention is to provide a. method for 4determining the productivity of the earth formation in a well and for producing a well,w that`1is tobe deepened or that may be deepe'neduat` a later date, which leaves the well bore producing of the well, and that may be easily, quickly and inexpensively-removed from the well at any time without resorting to expensive, uncertain shing operations.

Another object of this invention is to provide a method for accurately testing the productivity of the earth formation in a well and forproducing the uids from the earth formation that is characterized by the employment of well equipment that may be broken down and eliminated from the well by a suitable concentrated acid or other solvent agent, to leave the well bore free and unobstructed for subsequent operations.

l Another object of this invention is to provide a method for testing the productivity of the earth formations encountered in a Well and for producing the fluids from such formations that requires a minimum number of simple rapid operations that do not in any way endanger the well.

AA further object of this invention is to provide a method of the character mentioned that employs a well casing or liner and associated equipment that are substantially unaffected by the fluids that may be present in the well and, therefore, may be left in the well indenitely and yet are such that they may -be eliminated or removed from the well at any time bybreaking them down or dissolving them with material intro-v duced into the well. l V

The various objects and features of our invention wi11`be fully understood from `the following detailed description of typical preferred manners of carrying out the method of the invention,

ythroughout which description reference is made to the accompanying drawing, in which:

Fig. 1 is a vertical detailed sectional view of the lower portion 'of a typical well illustrating' apparatus in position in the Well for testing or producing the iiuds from the earth formation. Fig. 2 is a view similar to Fig. 1 showing the condition of the well following the removal of the testing or producing equipment in accordance with the method of the invention, and Fig. 3 is a vertical detailed sectional View of the lower portion of a well showing another form of casing or liner arranged in position to produce the free and entirely unobstructed at the completion of the `testing or producing operations.

'Another object of this invention is to provide a method for testingthe productivity of a well that utilizes equipment in the well suitable for a test oi vshort duration or for an extended test, which equipment may be left in the well following a 'favorable production test to be utilized in the well in accordance with the method of the iuvention.

The method of the present invention may be carried out with apparatus or equipment varying somewhat in character and the method is capable of variation to suit it for employment under the different `conditions that may exist in the well. We will proceed with a description of the well testing andproducing equipment illustrated in the adapter II and a ,for packing oil? the fluid in the well casing C from.

. conditions may require.

couplings I6. The aluminum Fig. 1 of the drawing and will then describe one' manner of performing the method of the inven- 'tion employing such equipment.

a tubular well string S detachably connected with packer I2 on the adapter II th'e earth formation being tested or produced.

The body III is an elongate tubular member or assembly adapted to be arranged in the well to receive the uids from the earth formation for.

the purpose of testing the productivity of the earth formation or for recovering or producing the fluids from the earth formation, or both. As illustrated in Fig. 1 oi the drawing, the body I0 is adapted to extend into or through the open portionA of the well bore B below the lower end of thevset well casing C.

and cementedin the usual `manner having its The well casing `C is set A lower portion and its shoe I3 embedded in a body of cement I4 resting upona shoulder I5 on the wall ofthe well bore B. The 4well bore IB, as illustrated, has been deepened or extended below the shoulder I5 to have an open por-tion A extending through theqstratum or strata D of earth formation to be tested or produced. The length oi the body I 0 depends upon the depth or extent of the open portion A of the well bore B and the body I0 may be formed of a single section or of a multiplicity of coupled or connected sections as In the case illustrated in the drawing the body I0 comprises several tubular sections IIIn coupled by threaded couplings I6.

Theliner body III is proportioned to extend into the open portion A oi' the well bore with suitable clearance andis adapted to be supported in any selected manner. In the'arrangement illustrated the lower end of the liner body I0 rests on the bottom'of the well bore B to be supported by this engagement.- -The liner body I0 illustrated in the drawing is provided with a multiplicity of spaced slots I8 to admit the iluids from the earth formation or strata D toit so that said fluids may pass upwardly through the body III and adapter I I to the string S.

'Ihe character of the material of which the liner body III is formed is an important feature ofthe invention. In accordance with the invention the body I0 is formed of a material that is soluble under conditions that the operator may establish in the well but that is resistant to and substantially unaffected by the fluids' that may be normally present in the well. The body I0 is formed of aluminum or an aluminum alloy. It isV to be understood that where reference is made to the body I Il as formed of aluminum or an aluminum alloy the body lIII is meant to include its one or more sections lllfa'nd'its one or more of which the body I0 is formed has a number of inherent physical properties or characteristics that render the body III practical, dependable and particularly adapted for its intended use. The body. I 0 being formed of aluminum or a suitable aluminum alloy has a substantial tensile strength so that there is little or no danger of the failing because of its own weight even though it may be of great length. The aluminum d and the aluminum alloys of which the body III 'may be formed have a: low specific gravity. AC1 cordingly, the body l0 formed of a material havor aluminum alloy strong and durable:

ing a substantial tensile strength andahlow speciiic gravity may be fabricated in substantially any desired lengthA without danger of parting or failing through its own weight. The substantial tensile strength of the aluminum or aluminum alloy of which the body I0 is constructed renders the threadsand like parts of the body structure.

Furthermore, the aluminum or aluminumalloy of which the body I0 is constructed isductile and readily machined so that the body I 0, the couplings I6, etc may be provided with good regular threads and connecting parts.

Wells often contain saline fluids and weak caustic fluids that may attack substantially pure aluminum. Accordingly, in some instances it may be preferred to construct the body I0 of an aluminum alloy that is non-corrosive and resistant to the action of the iluids encountered in wells. Silica o r. chromium, or both, may be alloyed with the aluminum of which the body I0 is to be constructed to produce an alloy that is resistant to the fluids encountered in deep wells. It is to be understood that the anoy of which the body I 0 is formed is soluble under conditions that .the operator may establish inthe well. Alloys of aluminum such as we have referred to 'are readily broken down by the materials or solvents to be later described.

The adapter II is body I0 with the lower end of the string S and to support the packer I2. The particular adapter "illustrated includes two relatiyely shiftable sections 2li and 2I. The section 2li is detachably secured to the lower endof the string Shaving a threaded socket 23 in its upper; end receiving the threaded lower part of the string S. The threads of the string S and the socket 23 vare lefthand `threads whereby the string may be easily- Unthreaded from the adapter II without endangering the other threaded connections of the string. The lower section 2I o1' the adapter string S. The upper end portion of the section 2| is shiftable in the opening 22 of the section 2 0 and a shiftable connection is provided between the two sections 20 and 2| This connection may comprise pins 21 on the section 2l shiftablein grooves 26 in the section 20. A downwardly and outwardlyinclined or tapered surface 28 is provided on the exterior of the adapter section 2| l cooperate with the packer I2.

.In accordancefwith the invention the adapter-P sections 20 and 2l are formed of aluminum or an aluminum alloy` of the character referred to above, whereby the adapter I'I may be broken well in the same mannery down ordissolved in the as the body I0.

The packer I2 may comprisean annular body of rubber, ork the like, arranged around the adapter section 2 I. internal surface 30 cooperable with the surface 28 and the upper by tn e lower` end of the adapter section 20. "Ihe periphery of the packer I2 is adapted to normally have suitable clearance withthe interior of the casing C so that the equipment may be readily run through the casing.

'I 'he string S isprovided to run or .lower the equipment intov the well and to receive and conduct awaythe fluids obtained from the tested or producing strata D. 'I'he string S may be a typiprovided to connect the linerl i 'I'he packer- I2 has a tapered end of the packer is engageable K cal tubular well string constructed of steel drill pipe or tubing.

The method of the present invention may employ the apparatus illustrated in Fig. 1 of the drawing to determine the productivity of the earth formation penetrated by the lower portion A of the well bore or to produce or recover the fluids from the said earth formation.l In carry-v ing out the method of the invention with the apparatus illustrated in Fig. 1 the body IIJ is fabricated to be of correct length, that is, to extend through the lower portion A of the well bore. The` adapter II provided with the packer I2 is secured to the upper end of the body I and the adapter in turn is connected with the lower end of the string S. The equipment is then ruri into the Well on the lower end of the string S to a position where the lower end of the body I0 rests on the bottom of the well bore.

Following the positioning of the equipment as just described., the Weight or a portion of the weight of the string S is imposed on the packer I2 through the medium of the shiftable adapter section 2U to expand the packer. The weight irn-` posed on the packer I2 causes the tapered surfaces 28 and 30 to cooperate in a manner to expand the packer I2 so that it seals with the interior of the Well casing C. The packer I2 maybe maintained under compression to seal with the interior of the casing C andf fully seal off the interior of the casing from the lower portion A of the well bore.

'I'he liquid that may be present in the lower portion A of the well bore may bepumped, bailed, swabbed or otherwise removed so that the fluids produced by the strata D will be uncontaminated. The fluids produced from the strata D will in most cases be under pressure to flow throughv the perforations I8 into the body I Il and up through the body I0, the adapter II and the string S. Under some conditions the strata D may produce fluids in a sufficient quantity and under parts in the Well.

In accordance with the present invention the equipment comprising the body I0 and the adapter I I may be removed or eliminated from the well when desired or necessary by decomposingdestroying, dissolving or breaking down the equipment in the well by the action of a solvent. In most cases it may be found desirable to disconnect the string S from the adapter section 20 and to withdraw the string S from the well before breaking down the equipment with the solvent.

It is to be understood that the body I0, the` adapter II and thepacker I2 may be removed chloric acid, or any other solvent that is capable of breaking down or dissolving aluminum and its alloys mentioned above, is introduced into the well to come into contact with the body I0 and the adapter II. Hydrochloric acid is effective as the solvent for breaking down the aluminum Hydrochloric acid is inexpensive, is usually readily available and reacts with aluminum to producealuminum chloride which is readily soluble in water and can be easily sufficient pressure to flow upwardly through the string S to the ground surface. In other instances it`I may be found necessary to withdraw the fluid produced into the string S by bailing or pumping' operations. If the equipment or apparatus is being employed to test the productivity of the earth formation the quantity of fluid produced from the strata D may be readily determined to accurately ascertain the productivity of the formation. If vthe equipment is being utilized to produce the well the fluid-produced from the strata D may be allowed to flow out through the string S or may be pumped from the string S in any of the well known manners.

Where the equipment is installed for the purpose of producing the well and it is found that the strata D does not produce in paying quanti- A ties it may be found desirable to deepen the well. In other cases it may be preferred to allow the well to produce through the string S or to pump the produced fluid through the string S and when the production is appreciably lessened the well may be deepened. In either event the equipment maybe easily and quickly removed from the well to leave it unobstructed for drilling and other operations. Where the equipment is .installed as described above, for the purpose of testing the` productivity ofthe earthiformation the equipment may be removed from the well in the Inanner to be described, immediately following the test, or it may be left in the well to produce the fluid from the strata D if it is. found that the strata D is producing in `paying quantities.

fiushed from the well. A strong or concentrated solution of hydrochloric acid may be introduced into theA well to dissolve the body l0 and other aluminum parts. The reaction of the hydrochloric acid with the aluminum parts in the well in the production of the water soluble aluminum chloride may be represented as follows:

2A1+6HC1=2A1C13+3H2 -Where hydrochloric acid is employed to remove or break down the body III andthe adapter` II it maybe found desirable or necessary to add an .inhibitor to the hydrochloric acid solution to thiocarbamide NHzCXSNHz; dibenzyl aniline disclosed in Patent No. 1,719,650 and represented by the formula CsH5N(CHeCeI-I5)2; dibenzyl amine 2(CsI-I5CH2)NH; 'or triphenyl` guanidine 2(CeI-I5NH)CNC6H5. While the three last named inhibitors are primarily for use with sulphuric acid H2SO4 they may be successfully employed with hydrochloric acid HC1 when the latter is used as the solvent in the presence of ferrous equipment. The proportion of the inhibitor used may, of course, be varied as the operating conditions demand. A solution of caustic soda (sodium hydroxide) is also effective in breaking down or dissolving the body I0. and adapter II in the well. A suitable quantity of a 20 per cent solution of sodium hydroxide may be introduced into the well to react with or break down the aluminum parts. This reaction may be repre-` sented as follows: y

First reaction:

2A1-|-6N'aOH-{6H2O=2A1(OH) 3+6NaOH+3H2 Second reaction; v t

A1 0Hi3+NaoH=2H2o+NaA1o2 x ',A sufficient quantity of the solvent material is introduced into the well to assure the complete dissolution of the body I and the adapter I I The body I0 and the adapter 'II being formed of aluminum oran aluminum alloy are quicklydissolved, decomposed or broken down bythe solution thus introduced into the well. The solvent or material(` employed to break down the body I0 and the adapter I I may fully decompose or eliminate the body and the adapter from the well to leave the well clear and free for subsequent operations.

The solvent or material for breaking down or decomposing the body I0 and the adapter II may be delivered to the lower portion of the well` to come into contact with the body I0 and the adapter II in any selected manner. For ex-l ample, it may be pumped into the well, lowered into the well in a bailer, or lowered into the well in a suitable container. 'I'he solvent or decomposing agent may be delivered to the lower portion of the well in such a manner that4 no appreciable'part of the agent or solvent is lost.

The packer being formed of rubber or the like may be substantially unaffected by the agent or solvent for breaking down the body I0 and the adapter I I and may remain in the well, as illustrated in Fig. 2. However, the packer may be easily destroyed, broken up or drilled away byl suitable tools, for example, by drilling tools thatA may be employed to deepen the well. Following the introduction of the acid, solvent, ,or decomposing agent into the Well a suitable periodv is allowed to elapse to assure the complete breaking down or dissolution of the aluminum body I0 and the aluminum yadapter `I I. Fig. 2.of the drawing illustrates the condition of the well followingthe elimination or dissolutionof the body I0 and the adapter II.

Following the breaking down or dissolving of the body I0 and the adapter II the solvent or dissolving medium may be removed fromthe well. Thel solvent or dissolving agent may be pumped, bailed, or flushed from the well. Subfor the installation of a tubular liner body |01 in the open well portion F. The liner body |01 may be supported or suspended in the well in any selected manner. In the particular case illustrated the lower end of the body lrests on the bottom of the well and the body is of suiiicient length to extend upwardly into the lower portion of the set casing C. The body |01 may be run into the well on the lowerend of a tubular well string similar to'the strings and following the setting or positioning of the body |01 the string may be detached from the body and withdrawn from the well. In the drawing we have shown the body |01 perforated or provided with a plurality of spaced perforations I8a that may be provided in the body I 01 prior tothe installation of the body in-the well. It is to be understood that the b'ody I 01 may be perforated following its installation in the well by anyof the well known perforating methods. 'I'he elongate tubular body |01 vmay be sectional and may be fabricated at the ground surface to be of the required length. A lefthandthread may be provided at the upper end part of the body I 01 to facilitate its detachable connection with a tubular setting string.

In accordance with the invention the body |01 isI formed 4of aluminum or an aluminum,I alloy of the character described above. The body |01 may be formed of an aluminum alloy that is resistant to the fluids encountered in wellsI so that it may remain in the well for a long period withweight so that it may be handled by light equipment and the body |01 may be fabricated to be of great length without danger of parting through its own weight. when the body 'lob is sequent to the removal of the solvent or dissolving agent the well maybe reconditioned for further production, may be deepened to penetrate lower productive strata, or any other required or .desired operations lmay be carried on in the well.

It is to be observed that the method provides for the rapid, eiiicient and economical testing of the `productivity ofthe earth formation in the open lower portion of the well or the production of the fluids from the sa,idearth formation, or'both, and the subsequent complete elimination of the equipment employed in the well in a safe.,I rapid and inexpensive manner. and producing operations may be carried out with the assurance that the equipment installed in the well may be quickly and safely removed,

or eliminated at any time. l

In Fig. 3 of the drawing we' have illustrated another manner oi'. carrying out the method of installed in the well as described above it con'- stitutes a casing or liner in the open well portion F to prevent caving and excessive sanding up of the well.

. If the open portion F of the well is to be tested to determine its productivity it may be desirable to rst pump, bail out or otherwise remove the mud and other fluids from the casing C and thev body |01. This willallow the fluids from the strata penetrated by the open well portion F to freely flow into the body |01 through its perfora- A tions I8". 'I'he fluid thus produced from the earth formation may pass upwardly through the casing C and whennecessary may be pumped or The various testing the invention. In the portion of the.well bore illustrated in Fig. 3I the casing C has its lower part cemented in the well and the well is extendedor drilled beyondJ the lower end of the casing to have an. open lower portion F. The

bailed from the well. If lit is found that the `strata penetrated by the open portion F of the well produce in paying quantities the body I 01 'may be left in the well to act as a production liner. In the event that the production test is unfavorable it may be found desirable to remove or eliminate the'body |01 from the well,`

The body |01 may be withdrawn from the well by a well string threadedly connected with its upper end or otherwise connected with it. If any difficulty is encountered in withdrawing the body |01 in'this manner or if it is not desired to req cover the body |01 the invention providesv a body of cement' Il provided around the lower part of the casing C seals offthe upper portion of the well from'the open 'lower portion F. The

openv portion F of the well maybe known to be productive in paying quantities or itmay be de- A sired to determine the productivity of the earth 'formation penetrated by theA open portion F- of the well. In either event the invention provides rapid and effectiver method for eliminating the body I0" from the well. The body |01 maybe dissolvedl broken down, or decomposed in the well by a. solvent or decomposing agent to leave the well bbre entirely free and unobstructed. A vsuitable concentrated or strong solution of hydrochloric acid, a'solution of sodium hydroxide, or any other material capable of breaking down `aluminum and its alloys is introduced to the lower portion of the well to come into contact with the body |01. This solvent or agent may be introduced into the well by means of a bailer, a pump or a container lowered into the well and a suicient quantity of the solvent or agent is employed to assure the complete dissolution of the body |01. The body 10b being constructed of aluminum or an aluminum alloy of the character referred' to is quickly broken down or dissolved by the solvent or dissolving agent. Following the breaking down or dissolving of the body Ib the solvent or dissolving agent may be pumped, hailed, swabbed or flushed from the well. The well is then in condition to be deepened or to be reconditioned for further production.

Having described only typical preferred manners of carrying out the method of our invention, we do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to ourselves any variations or modications that may appear to those skilled in the art or fall within the scope of the following claims.

Having described our invention, we claim:

1. The method of operating a well having ferrous metal structures therein and in which it may be advantageous to install a member that subsequently can be readily removed if desired, which method comprises forming said member of an aluminum alloy, positioning said member in the well and removing it when desired by dissolving said member with a strong hydroxide whereby the hydroxide will react and dissolve the aluminum alloy without detrimentally af-o fecting the ferrous metal structures.

2. The method of operating a. well having ferrous metal structures therein and in which it may be advantageous to install a member that subsequently can be readily removed if desired, which method comprises forming said member of an aluminum alloy, positioning said member in the well and removing it when desired by dissolving said member with sodium hydroxide whereby the sodium hydroxide will react with and dissolve the aluminum alloy under the temperature and pressure conditions normally existing in a well without detrimentally affecting the ferrous metal structures.

3. The method of operating a well having ferrous metal structures therein and in which it may be advantageous to install a member that subsequently can be readily removed if desired, which method comprises forming said member of an aluminum alloy, positioning said member in the well and removing it when desired by dissolving said member with an acid and employing an inhibitor which retards or prevents the acid acting detrimentally upon the ferrous metal structures.

4. 'Ihe method of operating a Well having ferrous metal structures therein and in which it may be advantageous to install a member that subsequently can be readily removed `if desired, which method comprises forming said member of an aluminum alloy, positioning said member in the well and removing it when desired by dissolving saidmember with hydrochloric acid together with an inhibitor which prevents or retards the acid acting detrimentally upon the ferrous metal structures.

5. I'he method of operating a well having fer` I rous metal structures therein and in which it may be advantageous to install a member that isapt to become immovably lodged in the well but which subsequently can be readily removed if desired which method comprises forming said member of an aluminum alloy, positioning said member in the well and removing it when desired bydissolving said 'member by causing it to chemically react with a substance which will chemically react with the aluminum alloy without detrimentally affecting the ferrous metal structures in the well.

ELWIN B. HALL.

ARTHUR L. ARMEN'I'ROUT. 

